This invention relates to the field of vehicle charging systems, and more particularly, this invention relates to a voltage regulator that regulates the output voltage of a vehicle charging system.
In automotive charging systems used in automotive vehicles, such as cars, trucks and motorcycles, the charging system includes an alternator or generator with appropriate windings, armature and stator components. The alternator or generator typically uses a voltage regulator to regulate the charging voltage and output current to provide consistent operation during varying loads that would create voltage drops and other operational problems. Current state-of-the-art vehicle charging systems design the voltage regulator with either a discrete transistor or a custom integrated circuit known as an Application Specific Integrated Circuit (ASIC). These prior art voltage regulator circuits often were hard-wired circuits that defined a specific function for a specific type of vehicle.
Some automotive designs have attempted to delete the voltage regulator altogether and use enhanced microprocessor controllers as part of the ignition module or computer module that controls all functions of the car. Other vehicle designs have used voltage regulators with advanced microprocessor functions that maintain a regulated voltage produced by a generator, but include advanced clock and memory circuits that store battery and power supply reference data, battery voltage and generator rotation speed, and determine how much the battery is being charged and at what rate at any point in time.
These advanced systems are expensive and it would be desirable if a more simplified voltage regulator circuit design could be used, especially on older vehicles as replacements to charge the battery in an efficient, controlled manner without having complicated circuits and memories, as in some prior art devices.
It is therefore an object of the present invention to provide a voltage regulator that regulates the output voltage of a vehicle charging system that is simple, efficient, and inexpensive, and overcomes the disadvantages of the prior art.
In accordance with the present invention, a voltage regulator of the present invention regulates the output voltage of a vehicle charging system that uses an alternator or generator, and includes a field winding. The charging system is connected to a vehicle battery and vehicle devices for supplying voltage and recharging the battery and powering vehicle devices. In accordance with the present invention, the voltage regulator includes a microcontroller, which is operative for monitoring the output voltages representative of monitored load changes within the vehicle. A power output circuit of the voltage regulator is controlled by the microcontroller and operatively connects to a field winding and battery. The microcontroller is operative for changing the field duty cycle of the generator or alternator by turning ON and OFF the power output circuit in a predetermined manner as established by the microcontroller based on monitored load changes within the vehicle. The power output circuit preferably comprises a power output transistor, such as a field effect transistor, but could be an IGBTs or similar device.
In yet another aspect of the present invention, the microcontroller is operative for changing the load response of the alternator or generator based on monitored load changes within the vehicle and provide a full output voltage after a predetermined period of time. The microcontroller is also operative for changing the time period in which the alternator or generator responds to monitored load changes within the vehicle. The microcontroller is operative for monitoring the input frequency of the alternator or generator and setting an output response rate dependent on the input frequency.
In yet another aspect of the present invention, the microcontroller has an output pin operatively connected to an ignition line circuit for monitoring ignition power and an output pin operatively connected to an indicator light sensing line for monitoring an indicator light status. The voltage regulator can be mounted within an alternator housing or on the backside of an alternator housing.
In yet another aspect of the present invention, the voltage regulator includes a voltage step-up or doubler circuit operatively connected to the power output circuit and microcontroller. The voltage step-up circuit is controlled from a common pin of the microcontroller, such that the microcontroller measures voltage on a transistor or diode in the voltage step-up circuit to determine temperature changes.
A method aspect of the invention is also disclosed and comprises the steps of monitoring within a microcontroller of the voltage regulator the output voltage representative of monitored load changes, and changing the field duty cycle of the generator or alternator by turning ON and OFF in a predetermined manner a power output circuit of the voltage regulator that is connected to the battery and a field winding as established by the microcontroller based on monitored load changes within the vehicle.